The development of semiconductor technology improves day by day rapidly, besides mainly focusing on the tiny packaging of the model, nowadays the data storage capacity is increasing gradually also. Therefore, with the increasing data quantity, the least time taken to process the same quantity data shows a higher efficiency in data processing. The straightest way to increase the semiconductor's processing rate is to increase the utilization ratio, but facing bottlenecks such as heatsink for high power, delay of signal time and electric magnetic interruption (EMI) when the data transmission is above Gb/s, which makes the fabrication of the higher performance semiconductor more difficult. Especially when the copper circuit is conventionally used as a carrier for data transmission, with the limitation of this material's natural conductivity, the achieved conductivity cannot be increased further, therefore the signal transmission rate cannot be increased by increasing the conductivity.
In addition, the metallic circuit structure for signal transmission is easy to have interruption from the outside noise or interference from the inner circuit, results in signal transmission error due to the interruption and interference during the signal transmission process; therefore, some protection methods are required for the signal transmission structure to prevent the interruption and interference occur to affect the signal, especially obvious in the high frequency transmission. The protection methods have increased some difficulties and extra structure design for the circuit design, results in increasing in the design cost and the fabrication cost, and therefore, the present condition is hard to make a breakthrough.
Moreover, the conventional signal transmission method is an analogue signal transmission method using electricity flowing through the conductor, but the signal processing methods inside the circuits nowadays mostly are digital processing; therefore a distortion may occur after conversion during the transmission process.
In order to resolve the drawbacks from the conventional analogue signal transmission structure, new technique of transmission method is using the optical signal to replace the electrical signal, and the most obvious improvement is that the optical signal almost will not be interrupted by the electromagnetic wave; therefore has a better signal transmission quality and reduce the signal transmission distortion. Also the structure design for preventing electromagnetic wave can be decreased, results in reducing the design and fabrication cost. Thus, using optics as a signal transmission method has become a direction in future development.
The conventional way of designing the optoelectronics transmission structure into the printed circuit board's structure, is to add a guiding layer containing organic waveguide film into the printed circuit board, then integrate the assembly of the optoelectronics components and driving components onto the printed circuit board; so the guiding layer can be used as the path for optical signal transmission to achieve the high speed transmission purpose. Referring to FIG. 1 for the U.S. Pat. No. 6,839,476, showing a saturated layer 12 forming above the bottom layer 11, and a plurality of grooves 12a are formed in the saturated layer 12; then place an optical fiber 13 into the groove 12a, and form another top layer 14 above the saturated layer 12 to embed the optical fiber 13 in the saturated layer 12; thereof the optical fiber 13 is a core 13a covered by a cladding 13b outside. Then the two terminals of the optical fiber 13 can be set up with optical emitter and receiver modules and optical passive components, to transmit optical signal by the optical fiber 13 to avoid the drawbacks from electrical signal transmission.
However, the optical fiber 13 is embedded in the saturated layer 12 and the groove 12a, thus the saturated layer 12 needs to have a grooving fabrication first, then places the optical fiber 13 into the groove 12a. An automatic placing movement, like the conventional insertion movement when inserting electronic components into a circuit board, completes the fabrication process of placing the optical fiber 13 into the groove 12a; therefore the speed of the fabrication is slow, and cannot achieve the rapid production purpose.
Moreover, the optical fiber 13 needs to be cut first according to the corresponding groove 12a length, and then places the optical fiber 13 into the groove 12a, which adds another process in the fabrication, therefore increases the fabrication difficulty; and the optical fiber 13 has different lengths, thereof increases the fabrication assorting difficulties, leads to the addition of the whole fabrication's process and complexity, and consequently increases the fabrication cost.
At forming the groove 12a on the saturated layer 12 to place the optical fiber 13, the gap between the groove 12a and another groove 12a needs to be relatively spaced in size design, in order to locate the optical fiber 13 into the saturated layer 12; the distance of the gap affects the wiring density, also the wiring density is affected by the size of the optical fiber 13's diameter, thus, cannot achieve the purpose of high density wiring.
Beside, the optical fiber 13 used to transmit the optical signal is a core 13a covered by cladding 13b, and the inner layer of the cladding 13b can be used as reflection surface to allow the optical signal reflects forward continuously via the inner layer of the cladding 13b to achieve the signal transmission purpose. The optical fiber 13 and the circuit board have different fabrication structure, thus needs to be fabricated by another independent fabrication process and increases the whole fabrication's difficulty; and to integrate the two different fabrication products increase difficulty as well, thus cannot achieve the mass production purpose to lower the fabrication cost.
Thus, the increasing fabrication difficulty and cost due to optical fiber 13 has to be embedded in the saturated layer 12, and further, failing to meet the high density wiring requirements, has become problems for industries desired to be resolved.
In addition, when using the optical fiber connector for the straight connection, because of the poor performance of the automatic production, a high accuracy alignment equipment is applied for the optical signal transmission and the alignment process is done by hand; this process not only increases the fabrication cost, but also reduces the productivity.
Beside, the use of optics for data transmission of the prior art comprises mainly by the signal processing components, such as the optical fiber, optical connector, optical/electrical converter and electrical/optical converter, thereby complete the digital data transmission; but the high accuracy optical alignment and the system are huge in dimension, which is a disadvantage in the current small and lightweight designing trend. Moreover, the above optical connector, optical/electrical converter and electrical/optical converter are placed on the surface of the package substrate, thus occupied part of the substrate surface and narrows the wiring area on the substrate surface.
Therefore, to provide an integrated device that can solve problems such as meet the small and lightweight electronic device requirement, lower the signal transmission loss, shorten the conduction path, reduce the noise, and thereby, leads to increase the electric performance, improve the bonding alignment, lower the fabrication cost increase the substrate surface's wiring area and increase the productivity, is a problem needs to be solved in industries.